Fan noise attenuator

ABSTRACT

In some embodiments, a passive noise attenuator reduces fan noise in an electronic system. Other embodiments are disclosed and claimed.

The invention relates to fans for electronic systems and more particularly to a fan noise attenuator for electronic systems.

BACKGROUND AND RELATED ART

Electronic devices are found in many living areas. Many such devices utilize fans for cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the invention will be apparent from the following description of preferred embodiments as illustrated in the accompanying drawings, in which like reference numerals generally refer to the same parts throughout the drawings. The drawings are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 is a schematic drawing of a fan assembly and sound absorbing structure according to some embodiments of the invention.

FIG. 2 is a schematic drawing of another fan assembly and sound absorbing structure according to some embodiments of the invention.

FIG. 3 is a partially cross section drawing of the fan assembly and sound absorbing structure from FIG. 2.

FIG. 4 is a partially cross section, partially schematic drawing of another fan assembly and sound absorbing structure according to some embodiments of the invention.

FIG. 5 is a partially cross section, partially schematic drawing of an electronic system according to some embodiments of the invention.

FIG. 6 is a flow diagram according to some embodiments of the invention.

FIG. 7 is a perspective view of another fan assembly and sound absorbing structure according to some embodiments of the invention.

FIG. 8 is a side view of the fan assembly and sound absorbing structure from FIG. 7.

FIG. 9 is a cross sectional view of another fan assembly and sound absorbing structure according to some embodiments of the invention.

FIG. 10 is a perspective view of a dual assembly according to some embodiments of the invention.

FIG. 11 is a perspective view of another electronic system according to some embodiments of the invention.

DESCRIPTION

In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of the invention. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the invention may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

With reference to FIG. 1, some embodiments of the invention may include a fan assembly 10 having an inlet side and an outlet side, and a sound absorbing structure 12 positioned on the inlet side of the fan assembly 10 and proximate to the fan assembly 10. For example, the sound absorbing structure 12 may be made from or include open cell foam or other sound absorbing material. The sound absorbing structure 12 may be substantially rotationally symmetric with an axis of the structure 12 aligned with an axis of the fan assembly 10. For example, the structure 12 may have a general conical shape, such as a truncated cone. Alternatively, the structure 12 may have a general pyramid shape, such as a truncated pyramid. Alternatively, the structure 12 may have any arbitrary shape which might be useful to absorb noise from the fan assembly.

With conventional fan assemblies, it may be believed by those skilled in the art that an obstruction on the inlet side of the fan would significantly reduce the cooling capacity of the fan. However, the inventors have discovered that, in many applications, much of the space in front of the fan is essentially dead air space. Advantageously, some embodiments of the invention provide the sound absorbing structure in the dead air space on the inlet side of the fan. Sufficient cooling air may be drawn around the sound absorbing structure with little or no cooling air flowing through the sound absorbing structure. Advantageously, positioning the sound absorbing structure on the inlet side of the fan may reduce noise from the fan (e.g. especially the noise emanating from the front of the fan that is most likely to be an annoyance to a user) with little or no negative effects on the fans capability to move air and subsequently provide cooling.

With reference to FIGS. 2-3, some embodiments of the invention may include a fan assembly 20 having an inlet side and an outlet side, and a sound absorbing structure 22 positioned on the inlet side of the fan assembly 20 and proximate to the fan assembly 20. The fan assembly 20 may include a fan 24 and a motor 26 connected to the fan 24, and the sound absorbing structure 22 may be attached to the motor 26. For example, the sound absorbing structure 22 may be adapted to support the motor 26 and fan 24 inside a chassis (not shown).

For example, with reference to FIG. 3, the sound absorbing structure 22 may include a rigid core 32 attached to the motor 26, and sound absorbing material 34 disposed around the rigid core 32. The sound absorbing material 34 may have a general conical shape with a smaller diameter end of the conical shape being nearer to the fan assembly 20. In some embodiments, the sound absorbing material 34 includes a series of annular cones having smaller diameter cones nearer to the fan assembly (for example, as described in detail below). Although shown as substantially solid around the core 32, in some embodiments the interior portion of the sound absorbing material 34 may be hollowed out to varying degrees.

In many conventional fan assemblies, a strut or bar extends inward from an outer housing of the fan assembly to support the central motor for the fan. A problem with this conventional structure is that noise is generated by the periodic passing of the fan blades past these struts. This noise is sometimes referred to as ‘blade pass frequency’ (BPF) noise. Advantageously, some embodiments of the present invention may eliminate such BPF noise by utilizing the sound absorbing structure as a strut-less mount for the fan motor. Because no struts may be required to support the motor, the blades of the fan may not pass any regular structures and the BPF noise is reduced or eliminated.

With reference to FIG. 4, some embodiments of the invention may include a fan assembly 40 having an inlet side and an outlet side, and a sound absorbing structure 41 positioned on the inlet side of the fan assembly 40 and proximate to the fan assembly 40, and an exit cone 42 positioned proximate to the fan assembly 40 on an outlet side of the fan assembly 40. In some embodiments, the fan assembly 40 comprises a fan 43 having a central hub 44, and the exit cone 42 may be attached to the central hub 44.

For example, the exit cone 42 may be adapted to reduce air disturbances on the outlet side of the fan assembly 40. For example, the exit cone 42 may transition the cross sectional area of the outlet air, acting as a diffuser nozzle to limit the rapid expansion of air flow and/or the periodic waking behind the fan motor. Advantageously, reducing air disturbances in the outlet air may reduce the fan noise.

Some embodiments of the invention may further include a fan housing 45 positioned around blades 46 of the fan 43, wherein the fan housing 45 defines an inlet bellmouth 47 which is adapted to cooperate with the sound absorbing structure 41 to promote an smooth and uniform inflow of air at directions transverse to an axis of the fan 43 (e.g. in the directions of arrows A, from the side more than directly in front of the fan 43). The fan housing 45 may be supported by mounting structures in a chassis other than the sound absorbing structure 41, such that no struts are required between the fan housing 45 and the fan motor.

With reference to FIG. 5. a system 50 includes a chassis 51, a system board 52 inside the chassis 51, an electronic component 53 on the system board 52, a fan assembly 54 inside the chassis 51, the fan assembly 54 having an inlet side and an outlet side, and a sound absorbing structure 55 positioned on the inlet side of the fan assembly 54 and proximate to the fan assembly 54. For example, as described in connection with FIGS. 2-3 above, the fan assembly 54 may include a fan and a motor connected to the fan, the sound absorbing structure 55 may be attached to the motor, and the sound absorbing structure 55 may adapted to support the motor and fan inside the chassis 51.

For example, the sound absorbing structure 55 may include a rigid core attached to the motor and sound absorbing material disposed around the rigid core. The sound absorbing material may have a general conical shape with a smaller diameter end of the conical shape being nearer to the fan assembly. For example, the sound absorbing material may include a series of annular cones having smaller diameter cones nearer to the fan assembly. The rigid core may be attached to a panel 56 of the chassis 51. For example, the panel 56 may be a front panel of the chassis 51. Alternatively, the rigid core may be attached to another panel of the chassis 51 (e.g. a back, side, top or bottom panel). Alternatively, the rigid core may be attached to an internal panel or other structure of the chassis 51. One or more panels of the chassis 51 may provide ventilation holes.

For example, the rigid core may be a plastic or metal rod having one or more threaded holes at the larger diameter end of the sound absorbing structure 51. The rod may be secured to the panel 56 with one or more corresponding fasteners. For example, one or more flush head metal or nylon bolts may pass through corresponding holes in the panel 56 and be threaded into the corresponding holes in the rod. Other conventional or hereinafter discovered suitable fastening methods may be utilized for attaching the sound absorbing structure 51 to the panel 56. As may be desirable, rubber or foam grommets or gaskets may be provided between the structure 51 and the panel 56 to isolate motor vibration noise (e.g. which may be transmitted through the rod).

The system 50 further includes an exit cone 57 positioned proximate to the fan assembly 54 on an outlet side of the fan assembly 54. For example, the exit cone 57 may be adapted to reduce air disturbances on the outlet side of the fan assembly 54. The fan assembly 54 may include a fan having a central hub, and wherein the exit cone 57 may be attached to the central hub. The system 50 may further include a fan housing 58 positioned around blades of the fan, wherein the fan housing 58 defines an inlet bellmouth which is adapted to cooperate with the sound absorbing structure 55 to promote an inflow of air at directions transverse to an axis of the fan. For example, the fan housing 58 may include posts 59 which may be mounted on the system board 52.

With reference to FIG. 6, some embodiments of the invention include providing a fan assembly (e.g. at block 60), and positioning a sound absorbing material in front of an inlet side of the fan assembly (e.g. at block 61). Some embodiments may further include disposing the sound absorbing material around a rigid core (e.g. at block 62), attaching the rigid core to a motor of the fan assembly (e.g. at block 63), supporting the motor in a chassis with the rigid core (e.g. at block 64), and/or attaching the rigid core to a panel of the chassis (e.g. at block 65).

Some embodiments of the invention may further include forming the sound absorbing material with a series of annular cones having increasing diameters along an axis (e.g. at block 66). Some embodiments of the invention may further include reducing air disturbances on an outlet side of the fan assembly with an exit cone (e.g. at block 67). For example, some embodiments may further include integrating the exit cone with a central hub of the fan assembly (e.g. at block 68). Some embodiments may further include promoting an inflow of air at directions transverse to an axis of the fan assembly with a fan housing positioned around blades of the fan which cooperates with the sound absorbing material (e.g. at block 69).

With reference to FIGS. 7-9, some embodiments of the invention may include a fan assembly 70 having an inlet side and an outlet side, and a sound absorbing structure 71 positioned on the inlet side of the fan assembly 70 and attached to the fan assembly 70, and an exit cone 72 attached to the fan assembly 70 on an outlet side of the fan assembly 70. In some embodiments, the fan assembly 70 comprises a fan 73 having a central hub 74, and the exit cone 72 may be integral with the central hub 74.

For example, the exit cone 72 may be adapted to reduce air disturbances on the outlet side of the fan assembly 70. For example, the exit cone 72 may transition the cross sectional area of the outlet air, acting as a diffuser nozzle to limit the rapid expansion of air flow and/or the periodic waking behind the fan motor. In some embodiments, the exit cone 72 may have a truncated cone shape or any other shape determined to be useful in reducing air disturbances in the outlet air. Advantageously, reducing air disturbances in the outlet air may reduce the fan noise.

For example, with reference to FIG. 9, the sound absorbing structure 71 may include a rigid core 81 attached to the fan motor (not shown), and sound absorbing material 83 disposed around the rigid core 81. The rigid core 81 may be attached to rigid plates 85 and 87 at respective ends of the rigid core 81. The sound absorbing material 83 may be captured in between the rigid plates 85 and 87. For example, the larger rigid plate 85 may provide a mounting surface with appropriate holes and/or structures to secure the sound absorbing structure 71 to a panel of an electronic system. For example, the smaller rigid plate 87 may provide a mounting surface with appropriate holes and/or structures to secure the sound absorbing structure 71 to the fan motor.

Some embodiments of the invention may further include a fan housing 75 positioned around blades 76 of the fan 73, wherein the fan housing 75 defines an inlet bellmouth 77 which is adapted to cooperate with the sound absorbing structure 71 to promote an inflow of air at directions transverse to an axis of the fan 73 (e.g. from the side more than directly in front of the fan 73). The fan housing 75 may be supported by mounting structures in a chassis other than the sound absorbing structure 71, such that no struts are required between the fan housing 75 and the fan motor.

The emergence of entertainment personal computers (ePCs) and a desire to have a similar look as other existing consumer electronic devices means that it may be desirable that the front face of an electronic system not be utilized as a venting area or fan intake (e.g. the common front bezel configuration typical today in PCs). These systems are most often oriented such the bezel faces the user. Insome embodiments, reducing or directing the fans noise emanating from the front of the chassis (bezel facing side) or toward the user may be an important element in delivering a quiet experience. Additionally, it may also be beneficial for an electronic system to emit less noise to be acceptable in a living area. Advantageously, some embodiments of the present invention may provide a passive acoustic attenuator for one or more side breathing axial fan(s).

In some embodiments, the sound absorbing structure 71 may be made of or include a sound absorbing material (e.g. open cell foam) and by its shape may provide passive noise attenuation. For example, the sound absorbing structure 71 may includes a series of annular cones made of a sound absorbing material. The annular rings form a serrated cross section with jagged edges 91, 93, 95, and 97 (e.g. see FIG. 9), which may be effective to create internal acoustic bounces to trap noise. In some embodiments, more or fewer rings may be provided.

Other known structures, shapes, and/or cross sections for passive acoustic attenuation may likewise find utility in the sound absorbing structure 71. Open cell foam material may be easily and inexpensively manufactured into the desired shape via any presently known or hereinafter discovered technique). For example, suitable techniques include the use of a revolved hot wire form into a block of foam, assembled die cut pieces or the use of reaction injection molding (RIM), among others.

In addition to dampening acoustic emissions and/or provide a strut-less mount for the fan motor, the sound absorbing structure (also referred to as an inlet cone) 71 may also help manage the fan air intake. For example, the inlet cone 71 may control the inlet air by reducing or removing shear flow interaction with the quiescent air above the motor hub. The fan may be mounted directly onto the inlet cone 71, so as the fan rotates it passes no fixed objects periodically and thereby reducing or removing the blade pass frequency (BPF) tones typically associated with fans.

With reference to FIGS. 10-11, some electronic systems may benefit from two or more of the fan assemblies described above. An example dual fan assembly 100 includes a first fan assembly 101 adjacent to a second fan assembly 103. An example electronic system 110 utilizes a dual fan assembly 111 in accordance with some embodiments of the invention. The electronic system 110 may include a power supply 113 which may include another fan for cooling the power supply. Although illustrated as a conventional fan, the power supply fan may optionally also utilize the passive noise attenuator as described herein.

The electronic system 110 may be configured as an ePC including such additional features as an optical media drive (e.g. a CD or DVD drive) and/or an internal hard disk drive 117. The front bezel of the ePC system 110 may include displays, buttons, knobs, jacks, and other user features. Advantageously, ventilation may be provided on one or more side panels 119 of the electronic system 110 and the dual fan assembly 111 according to some embodiments of the invention may provide a passive acoustic attenuator for two or more side breathing axial fan(s).

The foregoing and other aspects of the invention are achieved individually and in combination. The invention should not be construed as requiring two or more of such aspects unless expressly required by a particular claim. Moreover, while the invention has been described in connection with what is presently considered to be the preferred examples, it is to be understood that the invention is not limited to the disclosed examples, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the invention. 

1. An apparatus, comprising: a fan assembly having an inlet side and an outlet side; and a sound absorbing structure positioned on the inlet side of the fan assembly and proximate to the fan assembly.
 2. The apparatus of claim 1, wherein the fan assembly comprises a fan and a motor connected to the fan, and wherein the sound absorbing structure is attached to the motor.
 3. The apparatus of claim 2, wherein the sound absorbing structure is adapted to support the motor and fan inside a chassis.
 4. The apparatus of claim 2, wherein the sound absorbing structure comprises: a rigid core attached to the motor; and sound absorbing material disposed around the rigid core.
 5. The apparatus of claim 4, wherein the sound absorbing material has a general conical shape with a smaller diameter end of the conical shape being nearer to the fan assembly.
 6. The apparatus of claim 4, wherein the sound absorbing material includes a series of annular cones having smaller diameter cones nearer to the fan assembly.
 7. The apparatus of claim 1, further comprising: an exit cone positioned proximate to the fan assembly on an outlet side of the fan assembly.
 8. The apparatus of claim 7, wherein the exit cone is adapted to reduce air disturbances on the outlet side of the fan assembly.
 9. The apparatus of claim 8, wherein the fan assembly comprises a fan having a central hub, and wherein the exit cone is attached to the central hub.
 10. The apparatus of claim 9, further comprising: a fan housing positioned around blades of the fan, wherein the fan housing defines an inlet bellmouth which is adapted to cooperate with the sound absorbing structure to promote an inflow of air at directions transverse to an axis of the fan.
 11. A method, comprising: providing a fan assembly; and positioning a sound absorbing material in front of an inlet side of the fan assembly.
 12. The method of claim 11, further comprising: disposing the sound absorbing material around a rigid core.
 13. The method of claim 12, further comprising; attaching the rigid core to a motor of the fan assembly.
 14. The method of claim 13, further comprising: supporting the fan motor in a chassis with the rigid core.
 15. The method of claim 14, further comprising: attaching the rigid core to a panel of the chassis.
 16. The method of claim 11, further comprising: forming the sound absorbing material with a series of annular cones having increasing diameters along an axis.
 17. The method of claim 11, further comprising: reducing air disturbances on an outlet side of the fan assembly with an exit cone.
 18. The method of claim 17, further comprising: integrating the exit cone with a central hub of the fan assembly.
 19. The method of claim 18, further comprising: promoting an inflow of air at directions transverse to an axis of the fan assembly with a fan housing positioned around blades of the fan which cooperates with the sound absorbing material.
 20. A system, comprising: a chassis; a system board inside the chassis; an electronic component on the system board; a fan assembly inside the chassis, the fan assembly having an inlet side and an outlet side; and a sound absorbing structure positioned on the inlet side of the fan assembly and proximate to the fan assembly.
 21. The system of claim 20, wherein the fan assembly comprises a fan and a motor connected to the fan, and wherein the sound absorbing structure is attached to the motor.
 22. The system of claim 21, wherein the sound absorbing structure is adapted to support the motor and fan inside the chassis.
 23. The system of claim 22, wherein the sound absorbing structure comprises: a rigid core attached to the motor; and sound absorbing material disposed around the rigid core.
 24. The system of claim 23, wherein the rigid core is attached to a panel of the chassis.
 25. The system of claim 23, wherein the sound absorbing material has a general conical shape with a smaller diameter end of the conical shape being nearer to the fan assembly.
 26. The system of claim 23, wherein the sound absorbing material includes a series of annular cones having smaller diameter cones nearer to the fan assembly.
 27. The system of claim 20, further comprising: an exit cone positioned proximate to the fan assembly on an outlet side of the fan assembly.
 28. The system of claim 27, wherein the exit cone is adapted to reduce air disturbances on the outlet side of the fan assembly.
 29. The system of claim 28, wherein the fan assembly comprises a fan having a central hub, and wherein the exit cone is attached to the central hub.
 30. The system of claim 29, further comprising: a fan housing positioned around blades of the fan, wherein the fan housing defines an inlet bellmouth which is adapted to cooperate with the sound absorbing structure to promote an inflow of air at directions transverse to an axis of the fan. 